


Grillby's Got a Big Storm Coming

by ExplicitFeedFics



Category: Undertale (Video Game)
Genre: Ecto-Genitalia (Undertale), Ecto-Penis (Undertale), Ectobiology, Feeding Kink, Flirting, Food Kink, Gluttony, M/M, Mutual Pining, Porn, Weight Gain, feederism, idk it's not quite sexual yet so i'll leave it at this
Language: English
Status: In-Progress
Published: 2018-12-14
Updated: 2018-12-14
Packaged: 2019-09-18 01:33:15
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,662
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16985607
Author URL: https://archiveofourown.org/users/ExplicitFeedFics/pseuds/ExplicitFeedFics
Summary: Late at night, in the pouring rain, Grillby gets a knock at the pub's door. With an unexpected visitor, he finds out some things he'd never known and does something he thought he'd never do.





	Grillby's Got a Big Storm Coming

**Author's Note:**

  * Inspired by [Chili Fries Go Straight To Your Thighs](https://archiveofourown.org/works/10402644) by [UnderElk (orphan_account)](https://archiveofourown.org/users/orphan_account/pseuds/UnderElk). 



> It's been far, far too long since anything's been written here. That's my fault. But, after finally relearning how to force myself to start writing, I was able to finish part 1 of (presumably) 2 of a Grillby x Sans weight gain story. Still feel it's a reused formula, but I'm also struggling how else to do this sort of thing, so for noooow, it'll stay. Anyway, also have to point out that this fanfic definitely has at least some inspiration coming from the story Chili Fries Go Straight To Your Thighs by UnderElk. Certainly, that is a good fucking weight gain story. This won't be the same but I don't think you'd be hardpressed to find the similarities. But regardless, I hope you enjoy the beginning of this booty call (even though this first part has nothing inherently, entirely sexual. Oops).

There was a knock at the door to Grillby’s establishment, which had been closed and the door locked as Grillby was tidying and closing up. Typically, Grillby would see a knock after closing as some drunkard ignoring closing time, but seeing as it  _ was  _ raining outside, rather heavily in fact, Grillby thought it might be someone caught in the storm needing to call someone or dry off. He had no proof for this, but it just seemed more likely to happen now than most other days. So, sure, Grillby put the glass he’d just finished cleaning away in its proper place in a cupboard and walked over towards the door. While walking, only steps away the knock repeated. Surely, it must be someone in need of shelter or something of that nature, and he would be doing a good deed. He opened the door and immediately saw a familiar sight: Sans.

 

“Hey,” Sans greeted, his hands stuck firmly into his blue hoodie pockets even as the rainwater soaked it. It looked maybe twice as heavy as normal with just the water as it sagged and dripped.

 

Grillby, standing in the doorway, under the protective roof, sighed. Sans, even after the move up to the surface, still visited the pub practically daily. Therefore, the skeleton wasn’t unfamiliar, but he usually seemed to understand that closing time was closing time; he didn’t bother Grillby as he tried to close the bar. Grillby, one hand on the door and the other on the side of the doorframe. He shifted his weight and leaned on the latter hand and said, “What are you doing here, Sans?”

 

Grillby could swear something shifted in Sans’ expression as he replied, “Wanted to visit my favorite bartender made out of fire.” Lightning struck in the distance behind Sans as he spoke.

 

“Sans,” the thunder making its appearance as Grillby paused, “you know I’m closed.”

 

“Yeah, of course, but—”

 

“Then why are you here? Unless it’s to pay that tab of yours—”

 

“I’ll pay the tab eventually,” Sans sternly interrupted, his voice slightly raised. “But that’s not why I’m here. It’s… could I come in?” Sans’ left slipper began to slide off in a small stream of runoff water, before, looking down, he pushed back onto his foot using the ground.

 

Grillby waited for a second, thinking dually about why Sans would be at his bar at such a late time, as well as what might happen if he came in while he was trying to leave. After a few seconds of Grillby, stone-faced, contemplating while Sans half-nervously shifted in his spot, he took a quick breath, stepped aside, and exhaled. “Thanks.” Sans stepped in past Grillby, dripping some water onto him as he sauntered past. Grillby shut the door and followed the general path of the skeleton, who made his way towards a stool. Grillby grabbed a towel from behind the counter and set it down on the stool, momentarily stopping Sans. Sans sat down, getting water, still, all over the counter and floor. Grillby, behind the counter, picked up the next glass in the now small set of dirty glasses and began to clean it. 

 

Neither said a word to each other for a moment. Then, “So, you’re inside now. Why’re you here?”

 

“Well, heh, that’s an interesting one.”

 

“What have you done?”

 

“I haven’t done anything… necessarily. But that’s besides the point. It’s more… I wanted to something with you.”

 

“Clean the rest of these glasses?”

 

“No I meant…” Sans rubbed the back of his neck, “do  _ something _ with you.”

 

Grillby stood there, slowing his cleaning for a moment, confused. “Are you tal—”

 

“I heard from a friend of a friend that… well… you have a specific  _ thing.” _

 

“...What?”

 

“Well, Grillby, as far as I know, we’re friends… pals… chums… bu—”

 

“Keep going, I don’t know what you’re talking about.”

 

“Well, since we’re friends, I thought it might be fine to talk about, and maybe participate in, this stuff.” Sans paused. “Of course, now that I say that, I think the logic’s a little flimsy on that. Mostly, Grillby, I just wanted to do something with  _ you.” _

 

“...Are you alright? Have you taken something?”

 

“No, I’m fine.” Sans turned to the side for a second, clearly pretending to be distracted by something for a moment so that, for a few blessed seconds, he wouldn’t have to have eye contact with Grillby while relaying this utterly embarrassing information. “I mean, if I what I was told wasn’t right, I’ll leave and we can forget any of this ever even happened.” He began to stand up, before being stopped as a warm, orange hand was placed on his shoulder from over the counter.

 

“Look,” his orange complexion slowly becoming darker and its color cooler, “I don’t know who you got his from—”

 

“I’m not gonna tell.”

 

“Fine, but…” His hue quickly becoming a deep violet, “they’re definitely right.”

 

Sans quietly whispered, “I knew it.”

 

“Yeah. I’m a feeder...”

 

“Oh, perfect, I’m more a feedee.” Sans’ smile becoming more authentic, as he perked up, even as Grillby felt rather mortified.

 

“You… wow, this is all pretty sudden.”

 

“Yeah, sorry, but I was feeling the urge and couldn’t make this happen any more gently.”

 

“So, lemme get this straight.”

 

“God, you’d better not.”

 

“You’ve— oh. Oh. So, you’ve been lusting after me?” Grillby began.

 

“‘Fraid so.”

 

“You found out my fetish indirectly through some… apparently anonymous source?”

 

“Anonymous to you.”

 

“And you happen to have the same fetish, but on the receiving end?”

 

“It’s a wonderful miracle.”

 

“Well. I was hoping to get a normal amount of sleep tonight but, fuck it. I’ve always had a crush on you in the back of my mind, but I always ignored it; I tried to not think about it since you were just a patron who never paid, but if you’re not only feeling the same way, but also have the exact kink as me, then goddamnit, let’s do it.”

 

“Great.” Sans said, his tone teetering between joy and apathy, “Just to warn you, I’ve been told before, and I quote, ‘that I’m good at turning people to putty in my hands.’”

 

“I’ll... I’ll find out whether that’s true soon, I suppose. But, if you’ll allow it, two quick questions.”

 

“Hit me.”

 

“One, since you’re a skeleton, how do you actually eat and digest? Two, again as a skeleton, do you have… you know?” Grillby gestured his hand towards the crotch of    
Sans’ wet shorts.

 

“One and two are both: I can use magic to give myself a solution when I want.”

 

“How does that work?”

 

“Well, lemme show you.” Sans slipped off his heavy hoodie, setting it on the ground. Then he removed the white shirt beneath, revealing his, as Grillby felt, disappointingly nonattractive ribs and spine. Sans sat down at a booth, his legs hanging from the side of the seat.

 

“And…?”

 

Sans closed his eyes for a moment, and before Grillby materialized a blue stomach, coming into existence from behind the ribs and continuing down to his shorts. Then his sides and back looked average, looking rather anatomically correct. The belly, however, wasn’t quite what Grillby expected to see. Sure, the cyan blue made sense, but it was the form, the shape of it that struck Grillby as uncharacteristic of Sans. Especially with him proclaiming himself proudly as a feedee, it made no sense for his stomach to be as thin, nay,  _ thinner _ than Grillby’s! (Grillby wasn’t even really pudgy, but Sans here had what seemed to be a six-pack) His flat, perhaps even concave, belly had hints of the, muscles?, underneath and a neat, tight navel. It looked like, despite stating he would be of the type to gorge himself on large quantities of food, was the thinnest one in the room.

 

“Okay, so that’s where the food goes?”

 

“Yup.”

 

“If you don’t mind me asking, why are you so… lean?”

 

“Well, normally I engage in some self-stuffing every now and again,” Grillby became a little more purple, “but I haven’t done in the last few days, which is perfect for this occasion. That means,” Sans began to rub his hand up and down the blue surface, “I get to feel that much more of a change.”

 

“Okay, then, where’s the other bit?”

 

“Well, it’s right here,” Sans smirked, moving his other hand down, grabbing a large bulge which had materialized while Grillby was studying the stomach. His index finger and other fingers went to opposite sides of a slowly stiffening erection, which was pushing up, tenting the fabric. Sans slowly moved that hand up and down, speeding up the hardening, as its length became mostly known. He leaned back a tad, and purposefully thrusted his hips up a little as he adjusted his position. Sans tilted his head back and let out a small moan as his dick twitched. “I’m so horny for you right now, Grillby, that I might come before you even  _ touch _ me.”

 

“Well, I didn’t know you were this forward.” Grillby was even more purple than before. “I’m starting to feel a bit overdressed.”

 

“That’s cause you are. I love your ass in that outfit, and the vest/tie combination drives me mad, but for both of us to get the full experience, you’re gonna have to get that off.”

 

“Well’ if you don’t mind, I’ll go get some food to stuff you with, and then I’ll strip down for you.”

 

Sans shuddered. “You make me feel more excited than I thought possible, Grillby.”

 

“Such a flatterer.” Grillby chuckled, “Well, lemme go get some, like grease and lard, and then I’ll show you what my ass looks like outside this, horny.” Grillby left for the back as Sans’ underwear became sticky with precome. In just a moment, Sans would live out a sexual fantasy through someone who wasn’t only hot as fuck, but was also as into this as him. A (wet) dream come true.


End file.
